Extreme pressure lubricants



Patented Apr. 24, 1951 :21 j

OFFICE EXTREME PRESSURE LUBRICANTS Elmer B. Cyphers, Cranford, N. J., assignor to pment Company, a corpo- Standard Oil'Develo ration of Delaware No Drawing. Application August 31, 1948,

- Serial N0. 47,137

This invention pertains to extreme pressure lubricants and compositions for imparting extreme pressure or load carrying properties to lubricating oils. The invention also pertains to a method for preparing extreme pressure agents, incorporating elements such as sulfur, phosphorus, and the like, in such a manner that they will be available for suitable chemical activity under heavy load conditions.

4 As is well understood in the art, ordinary mineral base lubricating oils and greases. which are used to lubricate opposed metal surfaces are likely to fail under extremely heavy load conditions. For example, certain machine elements such as the hypoid gears commonly used in automotive vehicles may be subjected at timesto extremely heavy pressures of the order of hundreds of thousands of pounds per square inch.

If the film of lubricating oil separating the opposed elements fails, as it is likely to do under such pressure, the surfaces will contact each other directly, generating high temperatures due to friction, with resultant seizure or excessive wear and early failure. Extreme pressure additives containing active sulfur, phosphorus, or. chlorine, or two or more of these, are effective to react immediately with'the metal surfaces at their higher temperatures to form a protective metal sulfide, phosphide, or chloride film which serves temporarily as a lubricatin medium until the normal oil film between the parts can be 8 Claims. (01. 25.2-46.6)

reestablished. Extreme pressure additives are,

therefore, reactive with the metals they lubricate to form extremely thin protective films thereon when the temperature rises due to'normal, oil film failure. I

According'to the present invention, it has been discovered that compositions having extreme pressure properties and other desirable'properties for use in lubricating oil compositions, and the like, may be prepared from various esters of the alcohols which are derived from ordinary rosin and related materials by hydrogenation. For example, the abietic acid in rosin may be hydrogenated to convert it to an alcohol such as socalled hydroabietyl or dihydroabietyl alcohol. The alcohol so produced may be esterified in a well-known manner (such as by heating under pressure in the presence of a catalyst, while continuously removing water) with a long chain fatty acid which may be either saturated or unsaturated; The unsaturated acids are preferable for subsequent reactions which wil1 be pointed out below. Thus, the oleic acid ester of alcohols derived by the hydrogenation of resin is a par- V 2 g I ticularly preferred raw material, although other fatty acids such as stearic acid, palmitic acid, lard oil acids, sperm oil acids, synthetic aliphatic acids such as those produced by the oxidation of Waxes, olefins, or the aldehydes formed by the 0x0 reaction between olefins,. carbon monoxide and hydrogen. Otherand related acids having from 12 to 22 carbon atoms may be used for esterification.

A commercial product marketed as a hydroabietyl oleate and consisting apparently of a mixture of about 14% of a dehydroabietyl oleate, 37% dihydroabietyl oleate and 41% tetrahydroabietyl oleate, and 8% of un'saponifiable rosin derivatives (terpenes, etc.) was used in the following examples, but it is apparent that related esters would be equally useful and, in fact, the esters of abietic acid with long chain alcohols and the related hydrogenated acid esters of aliphatic alcohols having from 12 to 22 carbon atoms are contemplated as being satisfactory for the purpose of this invention. For example, among the alcohols which may be used are oleyl, lauryl, tetradecyl, sperm oil alcohols, cetyl, stearyl and synthetic alcohols such as those derived by the oxo reaction between olefins, carbon monoxide and hydrogen.

In producin the additive of the present invention, the ester is first reacted with elemental sulfur, for example by heating at a temperature somewhat in excess of 250 F., preferably in the range between 280 F. and about 450 F. The reaction time may vary from about one hour to about ten hours, although by the addition of a sulfurization catalyst such as a sulfur chloride the reaction may be hastened somewhat. The sulfurized product is then reacted with a bi-elemental phosphorus compound, for example P483, P4S7, P2S5, P013, P015, P205, etc. The phosphorizing reaction is suitably carried out by heating at a temperature in the range from about F. to about 300 F. until a product is obtained which is non-corrosive in the copper strip test which will be described below. In general, this may require a reaction time from about on hour to about 24 hours.

The invention will be more fully understood by reference to the following examples.

EXAMPLE 1 9'7 parts by weight of the commercial hydroabietyl oleate referred to abov were blended with .3 parts by weight of sulfur at a temperature of higher temperature for about two hours. The material was then permitted to cool to a temperature of 210 F. and then there were added 0.5 parts by weight of P483, the phosphorus sesqui-sulfide being mixed into the composition, and the mixture held at a temperature of 210 F. for twelve hours with continuous stirring. Upon analysis this product showed asulfur content of 3.12% and a phosphorus content of 0.30%. This material was subsequently added to mineral lubricating oil with test results which are shown in the table below.

In a patent application, Serial .No. 7l'2,050,'

now Patent No. 2,488,618 filed by-Ytheapreserit' inventor in conjunction with G. M. McNulty on November 25, 1942, there is described .a .comp o- I sition derived from rosin or methylated'rosin derivatives which, after treatment with a phosphorus sulfide, has extreme pressure propertieswhen used in lubricating oils. The product of the present invention, however, isquite distinct from that described in the cO-pending appliCa- 'tionin that thelong chain esters for "this present iiiv'erition do 'not have the property of depressing the viscosity index of the oils to 'wh ibh they "are added. The short chain esters hf the prior in 'vention-ar'e objectionable :in this-particular re "spec t, causing a loss of as much as tehi points in the viscosity index of the oils to whic'h'th'ey are-added. This property is of considerable importance where mineral oils of high viscosity index are not readily available, sincea viscosity index of at least 85 is considered -'n'ece's sary in the finished lubricant for many purposes.

EXAMPLEII 91parts of hydroa'bietyl 'ol'eate or commercial manufacture, as described above, "were combined with 9 parts byweight'of sulfura't a temperature EXAMPLE III lowed to cool to 210 F. and was thereupon reacted with 0.5 part by weight of Pisa at 210 F.

"for '1'2 hours. Analysis showed a sulfur content of 1.81% by weight, and a phosphorus content of about.0.25'%.

EXAMPLE IV 94 partsby-weight of the commercial hydroabietyl oleate of Exampe I and 6 parts of sulfur were heated, as in Example I, 0.5 part by weight 016 1 483 being added after the sulfur treatment. The resulting composition showed an analysis *of 5.I6'% sulfur and "0.26 %"phosphorus by weight. This material, as well -as that of'Exarn ple III, was'tested .in a 10% concentration in mine'ra l lubricating oil with-*an'd without 1'% of tric're'syl .phosphateyas indicated in the table which follows. Th'e'tricresyl phosphate increases moderately' theil'oad carrying properties of the lubric'ant, but'it will be understood that it may or may not be used, as desired. The composition of Exam-pleiIIwas-tested"also -=with52% of tricresyl phosphate, with moderate improvement in results.

The base oil used in the-tests indicated in the -=following table was a Pennsylvania" cylinder stock of 220 SVS. U. viscosity at 210 F. com-- 'bined with Mid-Continent acid refined lubricating oil-of S. U. viscosity at1210 F. The two 0115 were blended 'to produce-an SAEllO grade lubricant.

Load carrying tests of 280 and the "mixture washeated to-a temperature of 385 F. The mixture was-maintained atthat temperature with constant stirring for about 2% hours. It was found that this particular product was corrosive "to copper when tested as'a 10% concentration in 'miner'a llubrr- 'cating oil for one hour at 250 F. In'order to over cOme th'is corrosive property, 19 additionahparts by weightof hydroabietyl oleate were added and the mixture was further heated with stirring for i /2 hours at 3.85" F. The productjwas'then found to be non-corrosive (no blackening) when tested as above.

The sulfurized product was next treated with 0.5 part by weight'of P4S3 for lZhOu'rsJat 210 F. as in Example I. Analysis showed a sulfur foontent of "6.25% by weight, withsa phosphorus cont'e'nt of 0.25%.. Results .IOf i'adding :thismateiial to oil are indica'tedin the table. below.-

It will be understood, of course, that compositions of the .type referred to'above may be added in various'quantities to variousty-pes of oils, as will be obvious to those skilled in the art. They may be added to relatively :lightoils, such as oils of automotive engine grades for the-purpose of increasing-oxidation stability, although normally they will be used more widely in heavier oils such as those of SAE' 80, SAE 'or SAE grade-for the lubrication of hypoid'gears and other gears where extreme pressure proper ties-are desired. They-may also be used in cutting oils, andin-soluble cutting 'oils in conjunction with sodium sulfonates or other appropriate emulsify-ing agents. For usein gear oils, proportions- 'of5 to 20% by weight of the additivesare preferred, 10% being a common useful proportion; It willsbe understood, however, that proportions as -low as :about 1% may be employed,

For concentrates, to be added to oils by the consumer according to his needs, the additive products of this invention may be marketed straight or in to 80% solutions in mineral oil of appropriate grade. The mineral lubricating oils having viscosities between about 35 S. S. U. and 1,000 S. S. U. at 210 F. are preferred and the useful proportions of the additive are ordinarily between 1 and by weight, based on the total composition.

Various conventional additives may be employed in connection with the extreme pressure compound described above, such as thickeners, oiliness agents, oxidation inhibitors, tackiness agents, viscosity index improvers, pour point depress'ants, and the like. These materials may also be used in greases thickened with soaps, carbon blacks, silica gels and other known greaseforming materials.

In general, the materials to which the present invention is particularly applicable are the cycloaliphatic esters derived from rosin or from abietic acid or alcohol compounds, esterified with a long chain aliphatic material having from about 12 to 22 carbon atoms. As previously indicated, the long chain acid esters of cyclic alcohols are preferable, but the cyclic acid esters of long chain alcohols having the same general structure are also useful.

What is claimed is:

1. A composition consisting essentially of mineral base lubricating oil containing 1 to 20% by weight, based on the total composition, of a sulfurized and phosphorized ester of an abietic compound esterified with an aliphatic compound of 12 to 22 carbon atoms, wherein one of said esterifying compounds is a carboxylic acid and the other is an alcohol, said sulfurized and phosphorized ester being prepared by first combining about 91 to 97 parts by weight of the ester with 3 to 9 parts of sulfur and heating to a temperature between about 280 and 450 F. for a period of 1 to 10 hours, and thereafter treating the sulfurized product with about 0.5% by weight of a phosphorus sulfide at a temperature between about 150 and 300 F. for a period of 1 to 24 hours.

2. An extreme pressure additive for mineral base lubricants consisting essentially of sulfurized and phosphorized ester of an abietic compound and an aliphatic compound of 12 to 22 carbon atoms, wherein one of said esterifying compounds is a carboxylic acid and the other is a monohydric alcohol, said sulfurized and phosphorized ester being prepared by first com bining about 91 to 97 parts by weight of the ester with 8 to 9 parts of sulfur and heating to a temperature between about 280 and 450 F. for a period of 1 to 10 hours, and thereafter treating the sulfurized product with about 0.5% by weight of a phosphorus sulfide at a temperature between about 150 and 300 F. for a period of 1 to 24 hours.

3. An extreme pressure additive for mineral base lubricants consisting essentially of sulfur- 6 ized and phosphorized aliphatic carboxylic acid ester of hydroabietyl alcohol, wherein the esterifying aliphatic radical has between 12 and 22 carbon atoms, said sulfurized and phosphorized ester being prepared by first combining about 91 to 97 parts by weight of the ester with 3 to 9 parts of sulfur and heating to a temperature between about 280 and 450 F. for a period of 1 to 10 hours, and thereafter treating the sulfurized product with about 0.5% by weight of a phosphorus sulfide at a temperature between about 150 and 300 F. for a period of 1 to 24 hours.

4. The method of preparing an extreme pressure composition which comprises esterifying a hydrogenated rosin alcohol with an unsaturated fatty acid having a chain length of about 12 to 22 carbon atoms, heating about 91 to 97 parts by weight of said ester with about 3 to 9 parts of sulfur to a temperature of about 280 to 450 F. for a period of 1 to 10 hours, and thereafter reactin the sulfurized ester with about 0.5 part by weight of a phosphorus sulfide at a temperature of 150 to 300 F. for a period of 1 to 24 hours to incorporate both sulfur and phosphorus into said composition without rendering said composition corrosive to copper at moderate temperatures.

\ 5. A composition consisting essentially of about 1 to 20 parts by weight of sulfurized and phosphorized hydroabietyl oleate diluted with about to 99 parts of mineral base lubricating oil and about 10 to 20% of tricresyl phosphate, based on the weight of the sulfurized and phosphorized hydroabietyl oleate to form a lubricant having high load carrying properties, said sulfurized and phosphorized hydroabietyl oleate being prepared by first combining about 91 to 9'7 parts by weight of the ester with 3 to 9 parts of sulfur and heating to a temperature between about 280 and 450 F. for a period of 1 to 10 hours, and thereafter treating the sulfurized product with about 0.5% by weight of P483 at a temperature of about 210 F. for about 12 hours.

6. Composition as in claim 1 containing 5% to 20% of said sulfurized and phosphorized ester.

7. Composition as in claim 1 containing about 10% of said sulfurized and phosphorized ester.

8. Composition as in claim 1 containing about 10% of said sulfurized and phosphorized ester and about 1% to 2% of tricresyl phosphate.

ELMER B. CYPHERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,040,849 Holt May 19, 1936 2,130,740 Humphrey Sept. 20, 1938 2,211,306 Whittier Aug. 13, 1940 2,252,133 Morway Aug. 12, 1941 2,262,813 Morway Nov. 18, 1941 2,271,947 Morway 1 Feb. 3, 1942 2,415,837 Musselman Feb. 18, 1947 2,488,618 Cyphers et a1. Nov. 22, 1949 

1. A COMPOSITION CONSISTING ESSENTIALLY OF MINERAL BASE LUBRICATING OIL CONTAINING 1 TO 20 % BY WEIGHT, BASED ON THE TOTAL COMPSITION, OF A SULFURIZED AND PHOSPHORIZED ESTER OF AN ABIETIC COMPOUND ESTERIFIED WITH AN ALIPHATIC COMPOUND OF 12 TO 22 CARBON ATOMS, WHEREIN ONE OF SAID ESTERIFYING COMPOUNDS IS A CARBOXYLIC ACID AND THE OTHER IS AN ALCOHOL, SAID SULFERIZED AND PHOSPHORIZED ESTER BEING PREPARED BY FIRST COMBINING ABOUT 91 TO 97 PARTS BY WEIGHT OF THE ESTER WITH 3 TO 9 PARTS OF SULFUR AND HEATING TO A TEMPERATURE BETWEEN ABOUT 280* AND 450* F. FOR A PERIOD OF 1 TO 10 HOURS, AND THEREAFTER TREATING THE SULFERIZED PRODUCT WITH ABOUT 0.5% BY WEIGHT OF A PHOSPHORUS SULFIDE AT A TEMPERATURE BETWEEN ABOUT 150* AND 300* F. FOR A PERIOD OF 1 TO 24 HOURS. 